Un Nuevo Método de Identificación Basado en la Respuesta Escalón en Lazo Abierto de Sistemas Sobre-amortiguados

In this paper a new process identification method based in open loop step response of overdamped systems is presented. Initially the transient behavior of transfer functions with multiple real poles is analyzed, establishing analytical formulas to estimate the time it takes for these systems to reach certain points of his reaction curve to stimuli of the step type, including settling time for error criteria of 2% and 5%. Subsequently developed a method of identification using 3 points characteristic of the reaction curve (tk, yk), allowing estimate the order process N, the time constant T of multiple poles and delay time L of the approximate model. To evaluate the performance of the proposed method, 3 minimum phase and 1 non mimium phase transfer functions are used to compare the proposed method with other of identification methods found in the literature, as well as also, one model of a non-isothermal chemical reactor; establishing as efficiency index the root mean square error (RMSE) of the transient response and the frequency resposne of the identified models with respect to the original transfer functions with different signal to noise ratio (SNR) values. From the results obtained show that the proposed method achieves excellent approximation of the transient responses and frequency compared to other methods. From the results, it was observed that the proposed method obtains good approximations of the transient and frequency responses, being a simple method and requires a low computational load compared with others methods.